RNA-seq was used to analyze the transcriptional changes in sugar beet (Beta vulgaris L.) triggered by alkaline solution to elucidate the molecular mechanism underlying alkaline tolerance in sugar beet. Several differentially expressed genes related to stress tolerance were identified. Our results provide a valuable resource for the breeding of new germplasms with high alkaline tolerance. Alkalinity is a highly stressful environmental factor that limits plant growth and production. Sugar beet own the ability to acclimate to various abiotic stresses, especially salt and alkaline stress. Although substantial previous studies on response of sugar beet to saline stress has been conducted, the expressions of alkali-responsive genes in sugar beet have not been comprehensively investigated. In this study, we conducted transcriptome analysis of leaves in sugar beet seedlings treated with alkaline solutions for 0 day (control, C), 3 days (short-term alkaline treatment, ST) and 7 days (long-term alkaline treatment, LT). The clean reads were obtained and assembled into 25,507 unigenes. Among them, 975 and 383 differentially expressed genes (DEGs) were identified in the comparison groups ST_vs_C and LT_vs_C, respectively. Gene ontology (GO) analysis revealed that oxidation-reduction process and lipid metabolic process were the most enriched GO term among the DEGs in ST_vs_C and LT_vs_C, respectively. According to Kyoto Encyclopedia of Genes and Genomes pathway, carbon fixation in photosynthetic organisms pathway were significantly enriched under alkaline stress. Besides, expression level of genes encoding D-3-phosphoglycerate dehydrogenase 1, glutamyl-tRNA reductase 1, fatty acid hydroperoxide lyase, ethylene-insensitive protein 2, metal tolerance protein 11 and magnesium-chelatase subunit ChlI, etc., were significantly altered under alkaline stress. Additionally, among the DEGs, 136 were non-annotated genes and 24 occurred with differential alternative splicing. Our results provide a valuable resource on alkali-responsive genes and should benefit the improvement of alkaline stress tolerance in sugar beet.

中文翻译：

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甜菜 (Beta vulgaris L.) 响应碱性胁迫的转录组分析。

RNA-seq用于分析碱性溶液引发的甜菜（Beta vulgaris L.）的转录变化，以阐明甜菜耐碱的分子机制。鉴定了几个与胁迫耐受性相关的差异表达基因。我们的研究结果为高耐碱新种质的选育提供了宝贵的资源。碱度是一种高度压力的环境因素，会限制植物的生长和生产。甜菜具有适应各种非生物胁迫，尤其是盐和碱胁迫的能力。虽然之前已经对甜菜对盐胁迫的响应进行了大量研究，但尚未全面研究甜菜中碱响应基因的表达。在这项研究中，我们对用碱溶液处理 0 天（对照，C）、3 天（短期碱处理，ST）和 7 天（长期碱处理，LT）的甜菜幼苗的叶子进行了转录组分析。获得干净的读数并将其组装成 25,507 个 unigenes。其中，在对照组ST_vs_C和LT_vs_C中分别鉴定出975个和383个差异表达基因（DEGs）。基因本体（GO）分析表明，氧化还原过程和脂质代谢过程分别是ST_vs_C和LT_vs_C中DEG中最丰富的GO术语。根据京都基因和基因组途径百科全书，光合生物途径中的碳固定在碱性胁迫下显着富集。此外，编码 D-3-磷酸甘油酸脱氢酶 1 的基因的表达水平，谷氨酰-tRNA还原酶1、脂肪酸氢过氧化物裂解酶、乙烯不敏感蛋白2、金属耐受蛋白11和镁螯合酶亚基ChlI等在碱性胁迫下发生显着变化。此外，在 DEG 中，136 个是非注释基因，24 个发生差异可变剪接。我们的研究结果为碱响应基因提供了宝贵的资源，并有助于提高甜菜的碱胁迫耐受性。